Communication systems are known by a skilled person. A communication system may provide the user, or more precisely, user equipment or terminal, with connection-oriented communication services and/or connectionless communication services. An example of the first type is a circuit switched connection where a circuit is set-up with call set-up and admission control. This type of arrangement is used e.g. in public switched telephone networks (PSTN). An example of the connectionless communication services is a so called packet switched service. Packet switched communication is typically used in the Internet Protocol (IP) based networks. Both of the circuit switched and the packet switched services can be used for communicating packet data. Packet data services can be defined in general as services that are capable of transporting data units (data packets or similar data entities of fixed or variable length) between two signalling points, such as between two terminals or other nodes of the communication system.
In the connectionless services no circuit is set up, but each data entity itself contains an address. Upon arrival of the data entity in a node the address thereof may be looked-up in a table in the node, and the data entity is transported in the next hop to an address that corresponds to that address entry in the table. Instead of hops, in the circuit switched connections the nodes typically maintain information of how to route/switch each packet belonging to that flow. The circuit switched networks often have fixed-length packets called cells whereas packet-switched networks carry data units of variable length (e.g., the IP). However, there are also data networks that carry variable length data units in a connection-oriented architecture, such as Multi Protocol Labeled Switched (MPLS) networks.
A network that is capable of transporting data units or corresponding data entities between two or more nodes is referred to in the following as a data network. The data network may be a communication network that is based on use of a fixed line or wireless communication media. The fixed communication line network may comprise e.g. a public switched telephone network (PSTN), an integrated digital services network (ISDN) or an asynchronous data subscriber line (ADSL) network. The wireless communication network may be based on an appropriate public land mobile network (PLMN) standard, such as a GSM (Global system for mobile communication), general packet radio service (GPRS), enhanced data rate for GSM evolution (EDGE) or a third generation (3G) communication system such as the universal mobile telecommunication system (UMTS) or e.g. to a satellite based wireless communication standard. The wireless connection may be provided only for a part of the connection between the two nodes, that is, the fixed line networks may also comprise wireless communication.
A media gateway is a node that may be used for transforming media (e.g. speech or other communication) between the SCN (switched circuit network) and data network (such as the Internet Protocol based network) sides of the connection. An ITU-T recommendation draft H.248 titled ‘MEGACO’ (Media Gateway Control) defines a gateway control protocol that may be used in communication between a media gateway controller (MGC) and a media gateway (MG) enabling the gateway controller to control the gateway. The gateway control protocol is adapted for use in generation, connection and removal of different kinds of termination features. These operation include e.g. connecting a IP/UDP/RTP (Internet Protocol/User Datagram Protocol/Real-Time Transport Protocol) port to a certain time slot. In addition, the MEGACO gateway protocol may be used for transmitting information regarding instances such as tones that have been detected on the line and so on or request to generate required tones. It should be appreciated that the referenced ITU-T recommendation does not necessarily constitute the state of the art.
A quality of service (QoS) function has also been proposed for the packet switched networks. In general, the quality of service refers to feature by means of which different connections are provided with different service levels (i.e. different service classes). The QoS class to be used for a connection may depend e.g. on the agreement (subscription) between the user and the service provider, call type (e.g. normal call/emergency call) and so on.
Quality of Service (QoS) provisioning may be implemented using a so called differentiated services (‘DiffServ’) architecture. The term ‘DiffServ’ refers to differentiated service architecture for internet protocol (IP) networks. For example, the 3GPP (third generation partnership project) standardisation body has selected the DiffServ framework as the quality of service model for the core IP network. The QoS provisioning is obtained by appropriate marking of data units to be communicated in the IP network.
An IETF document RFC 2475 defines more particularly an architecture for implementing a scalable service differentiation in the Internet. The proposed differentiated services architecture performs its functions on the network level. Differently marked packets will receive a different priority in queuing and/or scheduling of nodes (so-called Per-hop-behaviour). The marking may depend dynamically on a time-averaged estimate of the data flow. The differentiated services is based on marking of the IP data packets with required data class and traffic contract information. For this the IPv4 (Internet Protocol version 4) header field ‘Type of Service’ (ToS) has been renamed as ‘DiffServ’ field. This has been proposed since the ToS field has never been widely used, and thus it could be renamed with a minimal impact. The DiffServ field is adapted to define parameters such as the QoS class, traffic contract and acceptable limits for the delay and packet loss.
It is believed that voice traffic may eventually (e.g. in the 3GPP release 2000 and beyond) run directly from a radio access network controller (RNC) of a cellular telecommunication network to the IP network or to the PSTN network through a media gateway (MGW) therebetween. This may require that the MGW is enabled to map the PSTN traffic to the IP-side quality-of service (QoS) classes and vice versa.
The inventors have found that if the media gateway is not notified about the QoS class to be used for a connection, the media gateway may set (e.g. mark) all speech packets to be sent in one QoS class (based on the TOS info) or may not set the QoS parameter at all. The inventors have also found that it might be advantageous if it could be possible to separate different speech calls or other calls within a call type class from each other (e.g. an emergency call from a “normal” or other lower priority call) in other devices that are based on a data network protocol, such as the IP.
What is needed is a standardised way for the media gateway controller to inform the media gateway on a call by call basis which service class is to be used for the data entities for a call.